Wood-pulp boiler.



E. M ORTERUD.

WOOD PULP 501mm,

APPLICATION man Ame. 1914.

Patented June 5, 1917 A A A WOOD-PULP BOILER.

Specification of Letters Patent.

Patented June 5, 1917.

Application filed August 6, 1914. Serial No. 855,516.

To all whom it may concern Be it known that I EINAR Momnnnn, a subject of the King of Norway, residing at Jelden, Norway,have invented certain new and useful Improvements in Wood-Pulp Boilers; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

' My invention relates to the manufacture of pulp or cellulose by a digesting process in which wood or other suitable material is kept at a high temperature in the presence of a suitable solution containing chemicals.

My invention consists in providing means for carrying out this manufacture in a more economical manner than heretofore has been possible.

It is a well known fact that in such processes before the temperature has reached 105410 centigrade no dissolving action takes place and even in the period between 110-125 centigradethe incrustive matter in the raw material is only very slowly dissolved. It is therefore clear that it is advantageous to make the first period of the digesting process, in which the temperature is raised, as short as possible, and as is well known by the direct process this is attained by supplying great quantities of steam and using a very strong solution. This method however can not be said to be an economical way of carrying out the process inasmuch as it causes great expenditures in chemicals.

When using the indirect method for heating the digester it is not possible to force the first period without employing an enormous heating surface. It is however very diflicult if not impossible to increase the number of heating tubes within the digester and moreover such apparatus will be very expensive. From these reasons in the indirect methods of carrying out the pulp manufacture the time necessary for accom plishing the digesting process is very long.

My invention now has for object to make it possible to carry out the indirect process in such a way that the time necessary for accomplishing the process is shortened and the whole process thereby more economical. I attain this result by heating the contents of a series of digester's successively by way of a great central heating apparatus, which by way of pipes and valves between the d1- gesters and the heating apparatus and between the several sections of the heating apparatus is connected with the digesters. In

carrying out the process I first utilize'the whole central heating apparatus through which the solution circulates or a certain part of the central heating apparatus to bring the temperature of the solution in one digester quickly to a suitable heat. I then shut ofl the connection between the central heating apparatus and said digester and make connection with another digester and so on. In the meanwhile the dissolving process is going-on in the first heated digester. If the central heating apparatus is divided into several sections, which from several reasons is preferable, two or more different parts of the central apparatus may be simultaneously used for different digesters. This arrangement also is preferable in so far as it allows repairin of parts of the central apparatus while ot er parts are working.

When carrying out the process in this manner it will be seen that it is possible in an economical manner to provide unlimited heating surface. The heating surface is also in this manner utilized in a most economical manner as it is always in working condition, it being successively connected with a whole series of digesters.

In the accompanying drawing I have illustrated diagrammatically an apparatus embodying my invention, wherein A designates five digesters, B a steam boiler for supplying steam to a central heating apparatus for heating the digesting fluid.

This apparatus preferably copm'sts, of three drums 0 each having a steam coil 0 passing through it. Each coil is connected at its top by a valved pipe 0? to a steam supply pipe D from the boiler B said coil being connected at the bottom by a valved pipe 6 with a return pipe E. By this arrangement all of the drums may be heated simultaneously from a single supply 4 pipe or one or more of the drums may be cut oil to permit of repairs.

The. digesting fluid is first heated in the drums, each of which is connected by a valved pipe 7 to a single pipe F which is connected by valve pipes f with the digesters at the top so that by turning on or oil th valves in the pipes f and f one or all of the drums may be laced in communication with any one or a l of the digesters.

Each digester is connected at its bottom by a valved pipe 9 to a single return pipe G which is connected to each of the drums at their bottoms by a valved pipe g.

This apparatus is used in the following manner:

The digesters are successively heated by way of the central heater in such way, that only one digester at a time isconnected with the heating apparatus. Supposing that the first digester has just been filled with raw material, the valves of pipes f, f, g, g, are opened and a circulation of the liquid will then take place between said digester and the heating apparatus. The other digesters are then shut oil from their connection with the pipes F, G. During the time when the first digester'is being heated, the second digester is emptied of its contents of cooked pulp, and new material is being filled in the digester. When the temperature in the first digester has been brought up to the necessary height, its connections with the pipes F, G, are closed, and the connections between the said pipes and the second digester are opened.

I claim:

1. The combination with a plurality of digesters, of a plurality of heaters for the digesting fluid, a fluid supply pipe common to all the digesters and heaters, a return naaaeso pipe common to all of said digesters and heaters, means to separately andselectively connect any of said digesters and heaters with said supply and return pipes, a steam generating apparatus, steam supply and return pipes connecting the latter with the heaters, and means to separately and collectively connect the heaters with the steam pipes.

2. The combination with a plurality of digesters, of a plurality of heating drums tively connect said fluid return-pipe with the bottoms of the digesters and drums.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

EINAR MORTERUD.

Witnesses RUTH LINDs'rRoM, CoNs'rANoE F. HANSEN.

for the digesting fluid, a heating coil in 

